A250800 Number of (3+1) X (n+1) 0..1 arrays with nondecreasing min(x(i,j),x(i,j-1)) in the i direction and nondecreasing absolute value of x(i,j)-x(i-1,j) in the j direction.

58, 180, 482, 1190, 2776, 6230, 13598, 29084, 61274, 127630, 263544, 540558, 1102982, 2241420, 4540290, 9173622, 18497880, 37239590, 74873806, 150386236, 301805898, 605284030, 1213273912, 2430926110, 4868936566, 9749335980

Offset: 1

Author

R. H. Hardin, Nov 27 2014

Keywords

• nonn

Examples

			Some solutions for n=4:
..1..0..0..1..0....0..1..0..1..0....1..0..0..0..0....1..0..1..0..0
..0..1..1..0..1....0..1..0..1..0....1..0..0..0..1....1..0..0..1..1
..0..1..1..1..0....0..1..0..0..1....1..0..0..0..1....1..0..0..1..1
..0..1..1..1..1....0..1..0..0..0....1..0..0..0..0....1..0..0..1..1
		

Links

• R. H. Hardin, Table of n, a(n) for n = 1..210

Crossrefs

Row 3 of A250797.

Formula

Empirical: a(n) = 5*a(n-1) - 8*a(n-2) + 3*a(n-3) + 3*a(n-4) - 2*a(n-5).

Empirical g.f.: 2*x*(29 - 55*x + 23*x^2 + 23*x^3 - 16*x^4) / ((1 - x)^2*(1 - 2*x)*(1 - x - x^2)). - Colin Barker, Nov 20 2018